Airbag device

ABSTRACT

Coupling spots are properly protected upon reception of gas pressure. A seam is possessed as a partition that partitions the interior of an airbag, and the seam is a coupling spot along which a frontal-side base fabric and a backside base fabric are coupled to each other. First and second reinforcing fabrics are provided on inner sides of the frontal-side base fabric and the backside base fabric, and the first and second reinforcing fabrics have remaining margins that are oriented toward the gas supply side in the downward direction rather than toward the seam, and each of the remaining margins functions as a shield wall against a flow of gas toward the seam.

INCORPORATION BY REFERENCE

The present application claims priority under 35 U.S.C.§ 119 to JapanesePatent Application No.2017-009793 filed on Jan. 23, 2017. The content ofthe application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to an airbag device.

BACKGROUND ART

In the airbag devices, a configuration is known in which an intermediatebase fabric is used to divide the interior of an airbag into a pluralityof compartments, a protective base fabric is provided within apredetermined compartment to cover an area around a gas entering port,and the protective base fabric is seamed integrally with a couplingportion along which the intermediate base fabric and a first base fabricare coupled to each other (see, e.g., Patent Literature 1). In PatentLiterature 1, the protective base fabric includes an extended portionthat extends toward the gas-entering-port side of each coupling portion,and a shield portion is provided in the extended portion, and the shieldportion is raised upward in a loop manner.

CITATION LIST Patent Literature

[Patent Literature 1] JP-A No. 2000-238604

Summary of Invention Technical Problem

However, in a conventional configuration, because the shield portion isprovided to be raised upward in a loop manner, a manufacturing processfor the shield portion is required separately, so that the configurationis complicated. Further, when the shield portion is slanted by receivingthe gas pressure, a gap in communication with the coupling portion iscreated between the loop and the intermediate base fabric, so that thecoupling portion is easily exposed to gas.

To address this, it is an object of the present invention to provide, ina simple configuration, proper protection for a coupling spot when gaspressure is received.

Solution to Problem

To achieve the above object, an aspect of the present invention providesan airbag device that includes an airbag (40) and a partition element(51S), the airbag (40) being made of base fabric and formed in a bagshape to deploy by being supplied with gas, the partition element (51S)partitioning the interior of the airbag (40). The airbag device has, asthe partition element (51S), a coupling spot along which a base fabric(61) of a frontal side of the airbag (40) and a base fabric (62) of abackside of the airbag (40) are coupled to each other. The airbag deviceincludes reinforcing fabrics (63, 64) that are provided respectively onan inner side of the base fabric (61) of the frontal side and an innerside of the base fabric (62) of the backside. Each of the reinforcingfabrics (63, 64) has a remaining margin (91) in a location closer to agas supply side than the coupling spot (51S) is located. The remainingmargin (91) is oriented toward the gas supply side to function as ashield wall against a flow of gas toward the coupling spot (51S).

In the above configuration, the remaining margin (91) of each of thereinforcing fabrics (63, 64) may be longer than a separation distance(Z) between a proximal end of the remaining margin (91) and the couplingspot (51S).

Further, in the above configuration, the airbag device may have couplingspots (58S, 71S), as another coupling spot, in a location closer to thegas supply side than the coupling spot (51S) is located. One (58S) ofthe coupling spots (58S, 71S) may provide coupling between one (63) ofthe reinforcing fabrics (63, 64) and the base fabric (61) of the frontalside, and the other coupling spot (71S) may provide coupling between theother reinforcing fabric (64) and the base fabric (62) of the backside.And the remaining margin (91) of each of the reinforcing fabrics (63,64) may extend longer from the another coupling spot (58S, 71S) in thereinforcing fabric (63, 64) than a separation distance (Z) between thecoupling spot (51S) and the another coupling spot (58S, 71S).

Further, in the above configuration, the partition element (51S) may bea coupling spot along which a pair of the base fabrics (61, 62) arecoupled together while the reinforcing fabrics (63, 64) are laid betweenthe base fabrics (61, 62), the pair of base fabrics (61, 62) forming thefrontal side and the backside.

Further, in the above configuration, each of the reinforcing fabrics(63, 64) may include a plurality of reinforcing fabrics (63, 64) thatmay be laid one on top of another on the inner side of the base fabric(61) of the frontal side and the base fabric (62) of the backside.

Further, in the above configuration, the reinforcing fabrics (63, 64)may be situated respectively on the base fabrics (61, 62) that form thefrontal side and the backside, and may have the remaining margins (91A)longer than the remaining margins (91) of the reinforcing fabrics (63,64) on the opposite side from the base fabrics (61, 62).

Further, in the above configuration, the reinforcing fabrics (63, 64)may be provided respectively on the inner side of the base fabric (61)of the frontal side and on the inner side of the base fabric (62) of thebackside, and may have the remaining margins (91) that overlaps eachother when the remaining margins (91) are bent by pressure of the gas.

Advantageous Effects of Invention

In the aspect of the present invention, as the partition, the couplingspot along which the frontal-side and backside base fabrics of theairbag are coupled to each other is possessed. The reinforcing fabricsare provided respectively on the inner side of the frontal-side basefabric and the inner side of the backside base fabric of the airbag.Each of the reinforcing fabrics has the remaining margin in a locationcloser to the gas supply side than a location of the coupling spot alongwhich the frontal-side base fabric and backside base fabric are coupledeach other. The remaining margin is oriented toward the gas supply sideto function as a shield wall against gas, the gas flowing toward thecoupling spot. Thus, the coupling spot is able to be protected over awide region, and the partition for partitioning the interior of theairbag is able to be properly protected in a simple configuration.

Further, because the remaining margin of each reinforcing fabric has alength longer than the separation distance between the proximal end ofthe remaining margin and the coupling spot, the function of theremaining margin as the shield wall is improved.

Further, the coupling spots are further possessed as another couplingspot in a location closer to the gas supply side than the coupling spotis located. One of the coupling spots provides coupling between one ofthe reinforcing fabrics and the frontal-side base fabric, and the othercoupling spot provides coupling between the other reinforcing fabric andthe backside base fabric. And the remaining margin of each reinforcingfabric extends longer from the another coupling spot in each reinforcingfabric than a separation distance between the coupling spot and theanother coupling spot. As a result, protection for each seam is enabled.

Further, because the partition is the coupling spot along which the pairof base fabrics, together with the reinforcing fabrics between the basefabrics, is coupled together, the pair of base fabrics forming thefrontal side and the backside, the coupling spot in which a plurality offabrics are laid one on top of another is able to be protected.

Further, because the reinforcing fabrics are laid one on top of anotheron the inner side of each of the frontal-side and backside base fabrics,the function of the remaining margin as the shield wall is enhanced.

Further, because the reinforcing fabric is situated on each of the basefabrics that form the frontal side and the backside and the reinforcingfabric has the remaining margin longer than the remaining margin of thereinforcing fabric on the opposite side from the base fabric, theremaining margin on the base fabric side can be more easily bent thanthe remaining margin that is away from the base fabric. Thus, even ifthe gas pressure is relatively low, the remaining margins can facilitateprotection.

Further, because the reinforcing fabrics are provided respectively onthe inner side of the frontal-side base fabric and the inner side of thebackside base fabric and the reinforcing fabrics have the remainingmargins that overlap each other when the remaining margins are bent bythe gas pressure, the function of the remaining margin as the shieldwall is further enhanced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a left side view of a motorcycle equipped with an airbagdevice according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a sectional structure of a retainer ofthe airbag device as well as the peripheral configuration.

FIG. 3 is a view of a deploying inflating airbag when viewed from thefrontal side (the occupant side).

FIG. 4 is a view of the deploying inflating airbag when viewed from thebackside (the side opposite from the occupant).

FIG. 5 is a diagram illustrating a deployment status of the airbag on atime-series basis.

FIG. 6 is an exploded diagram of the airbag.

FIG. 7 is a top view of a first reinforcing fabric of the airbag.

FIG. 8 is a schematic side view illustrating a frontal-side base fabric,first and second reinforcing fabrics and a backside base fabric duringairbag non-deployment.

FIG. 9 is a schematic side view illustrating the frontal-side basefabric, the first and second reinforcing fabrics and the backside basefabric during airbag deployment.

FIG. 10 is a diagram showing an example embodiment of the remainingmargins with different lengths.

FIG. 11 is a diagram showing an example embodiment of a plurality of gaschambers with different widths.

DESCRIPTION OF EMBODIMENTS

Embodiments according to the present invention will now be describedwith reference to the drawings.

It is noted that, throughout the description, references to directionssuch as front, rear, left, right, up and down directions are made withreference to a vehicle body unless otherwise stated. It is also notedthat, in all the drawings, reference sign FR denotes the forwarddirection of the vehicle body, reference sign UP denotes the upwarddirection of the vehicle body, and reference sign RH denotes therightward direction of the vehicle body.

FIG. 1 is a left side view of a motorcycle 1 with an airbag device 30according to an embodiment of the present invention. FIG. 1 illustratesthe state in which an airbag 40 deploys and expands.

The motorcycle 1 includes a swing unit 4. The swing unit 4 is formed ofa combination of an engine 2 and a power transmission mechanism 3. Arear wheel 5 of the motorcycle 1 is rotatably supported at a rearportion of the swing unit 4, while a front wheel 6 is rotatablysupported at a lower portion of a pair of left and right front forks 7.A bridge 8 is placed across the upper portions of the pair of left andright front forks 7. A steering shaft 9 is arranged upright at thecenter in the vehicle width direction of the bridge 8. A handlebar post9A is provided on an upper portion of the steering shaft 9. A handlebar10 is attached to the handlebar post 9A, and the handlebar 10 isprovided for steering the motorcycle 1 to the left/right. The steeringsystem (steering device) of the motorcycle 1 is made up of the frontwheel 6, the front forks 7, the steering shaft 9, the handlebar 10 andthe like.

A body frame 11 includes a head pipe 12 and a main frame 13. The headpipe 12 supports rotatably the steering shaft 9. The main frame 13extends downward from the head pipe 12 to the rear. The body frame 11further includes a pair of left and right side frames 14 and a pair ofleft and right seat frames 15. After the left and right side frames 14extend rearward from a lower portion of the main frame 13, the left andright side frames 14 extend upwardly toward the rear. The left and rightseat frames 15 extend upwardly from rear portions of the side frames 14toward the rear.

The swing unit 4 is supported via a link member 14A at lower rearportions of the pair of left and right side frames 14, and the swingunit 4 is supported in a vertically swingable manner. An air cleaner 28is mounted on an upper portion of the swing unit 4. The air cleaner 28is connected to the engine 2 through a not-shown throttle body and/orthe like. The seat frames 15 support a seat 16 on which the occupant isto sit. The seat 16 is configured as an integral-type seat, the seatincluding a combination of a main seat 17 and a pillion set 18. Therider sits on the main seat 17 and a pillion passenger sits on thepillion seat 18. The seat 16 is placed rearward and downward of thehandlebar 10.

The motorcycle 1 is covered with a resin-made body cover CV. The bodycover CV includes a front cover 21 and a pair of left and right frontside covers 22. The front cover 21 covers a body front section fromfront. The left and right front side covers 22 extend rearward from theleft side and right side of the front cover 21 to cover the left sideand right side of the body front portion, respectively. A visor (alsocalled “windscreen”) 21A is mounted on an upper portion of the frontcover 21. The visor 21A is raised rearward from the front in a rearwardand upward direction in side view so as to guide the traveling air fromthe front in the rearward and upward direction.

An inner cover 23 is installed to the pair of left and right front sidecovers 22 from the rear. The steering shaft 9, the head pipe 12, aretainer 31 of the airbag device 30, and the like are placed between thefront side covers 22 and the inner cover 23.

The retainer 31 is a member for housing an airbag 40. The retainer 31 isplaced immediately behind the steering shaft 9 and the head pipe 12 bybeing supported by a stay 13A. The stay 13A extends rearward from anupper portion of the main frame 13 to support the retainer 31.

A center cover 24 is continuous with a lower portion of the inner cover23. The center cover 24 constitutes a cover for covering the main frame13 from the upward and rearward direction, the cover being located onthe inner side between both feet of the rider when he/she is sitting onthe main seat 17. Also, the center cover 24 serves as a leg straddleportion over which the rider's leg steps when he/she gets on/off themotorcycle 1.

A pair of left and right rear side body covers 29 is placed rearward ofthe center cover 24. Each of the pair of left and right rear side bodycovers 29 covers an area below the seat 16, and also the left and rightrear side body covers 29 extend in the vehicle longitudinal direction tocover a body rear section from the left and right sides.

A pair of left and right step floors 20 on which the occupant restshis/her feet is placed in a central lower area in the vehiclelongitudinal direction. The step floors 20 are continuous with lowerportions of the center cover 24, and the step floors 20 extend in thevehicle longitudinal direction at a location downward of a front portionof the seat 16. Under cowls 26 cover areas below the step floors 20.

Above the center cover 24, a straddle space 19 is created between thehandlebar 10 and the seat 16. The occupant passes his/her leg throughthe straddle space 19 in order to ride on the motorcycle 1. In order toride the motorcycle 1, the rider (occupant) passes his/her leg throughthe straddle space 19, then the rider (occupant) sits on the seat 16(main seat 17), and then the rider (occupant) rests his/her legs on theleft and right step floors 20, the left and right step floors 20 beingprovided in a central lower area in the vehicle longitudinal direction.

The retainer 31 of the airbag device 30 is provided in the straddlespace 19. That is, while the airbag 40 is housed within the retainer 31,the airbag device 30 is provided in the straddle space 19. The retainer31 is placed to be inclined upwardly toward the rear to extend along arear wall of the inner cover 23. This enables ensuring of a widestraddle space 19 even if the airbag device 30 is located. By virtue ofthis, the ease of getting on/off is able to be maintained for theoccupants. Incidentally, reference sign LC in FIG. 1 indicates thecenter axis of the retainer 31, and the center axis LC is inclinedupwardly toward the rear at the center of the vehicle width direction.

The airbag device 30 includes the retainer 31, the airbag 40 and asingle inflator 32. The airbag 40 is housed within the retainer 31. Theairbag 40 is formed by sewing base fabric. The inflator 32 delivers gas(gaseous matter) into the airbag 40 to cause the airbag 40 to deploy andexpand.

FIG. 2 is a diagram illustrating a sectional structure of the retainer31 as well as the peripheral configuration. Incidentally, FIG. 2 showsthe airbag 40 in a folded state.

The retainer 31 is a box body. The box body has a lid member on a topportion. The lid member is opened by receiving a reactive force upondeployment of the airbag 40. The retainer 31 has a mounting hole formedin a bottom plate 31 a. The mounting hole is formed in order to attachthe inflator 32. The inflator 32 has a flange 32 a of a larger diameterthan the mounting hole. The inflator 32 is inserted into the mountinghole until the flange 32 a abuts on the underside of the bottom plate 31a.

The flange 32 a and the bottom plate 31 a are fastened together atspaced positions in the circumferential direction with a plurality offastening members 34. Thus, the inflator 32 is secured to the retainer31.

A bag ring (also called a “retainer plate”) 33 is placed on the topsurface of the bottom plate 31 a. The bag ring 33 is formed to have alarger diameter than that of the flange 32 a. A spot of a largerdiameter of the bag ring 33 than the flange 32 a is fastened to thebottom plate 31 a of the retainer 31 at spaced positions in thecircumferential direction with a plurality of fastening members 35.

As illustrated in FIG. 2, a lower portion of the airbag 40 is insertedthrough the fastening members 35 between the bag ring 33 and the bottomplate 31 a of the retainer 31. A shoulder 31 b is formed in the bottomplate 31 a of the retainer 31, and the shoulder 31 b protrudes downwardtoward the rim beyond the abutting spot of the flange 32 a. Thus, in aposition outside the rim of the flange 32 a, clearance S is createdbetween the bag ring 33 and the bottom plate 31 a of the retainer 31.

That is, in the configuration, the bottom plate 31 a of the retainer 31is provided with the shoulder 31 b, and the shoulder 31 b protrudesdownward to create the clearance S between the bag ring 33 and theshoulder 31 b. Then, the bag ring 33 and the shoulder 31 b are fastenedtogether with the fastening members 35 so that the bag ring 33 and theretainer 31 are secured together. In addition, the airbag 40 is attachedin the area of the clearance S in which the fastening members 35 arelocated.

In this manner, the airbag 40 is able to be attached through the use ofthe fastening members 35 for the securing of the bag ring 33 and theretainer 31 to each other, and also the attachment spot of the airbag 40is able to be spaced downward from the bag ring 33. Accordingly, theattachment spot of the airbag 40 is not more easily affected by pressureand/or temperature of gas in the bag ring 33, and this can cause furtherimprovement in thermal toughness.

Note that the storage state of the airbag 40 may be set to be in a rollform, accordion form or the like as appropriate with consideration ofparameters such as a deployment direction of the airbag 40, a deploymentspeed of the airbag 40, and/or the like.

The motorcycle 1 is equipped with an acceleration sensor (not shown) fordetecting impact. The acceleration sensor is electrically connected to acontroller (not shown), and in turn the controller is electricallyconnected to the inflator 32. Based on the detected acceleration, thecontroller determines at once whether the airbag 40 should be activatedor not activated. If activation is determined, the inflator 32 isactivated to deliver gas into the airbag 40 so that the airbag 40deploys and also inflates. Hereinafter, “to deploy and also inflate”will be represented as “deployment inflation” as appropriate.

FIG. 3 is a view of the deploying inflating airbag 40 when viewed fromthe frontal side (the occupant side). FIG. 4 is a view of the deployingexpanding airbag 40 when viewed from the backside (the side oppositefrom the occupant).

The airbag 40 has a bag shape of which the width is increased gradually(fanned out) from a neck portion 41 toward the top. The neck portion 41serves as an entering port through which gas is introduced from theinflator 32. In the airbag 40, a maximum width spot forms a head facingportion 42. The head facing portion 42 is a portion that is to face thehead of the occupant during inflation deployment of the airbag 40.

An abut portion 43 is formed integrally with a top portion of the headfacing portion 42. The abut portion 43 constitutes the uppermost portionof the airbag 40. The abut portion 43 is a portion that is to abut on acollision object during inflation deployment of the airbag 40. Thecollision object exists forward (in front of the occupant). The abutportion 43 is formed in a protrusion shape, and the protrusion shapeprotrudes upward from a widthwise central region of the head facingportion 42.

A linking portion 44 links the neck portion 41 and the head facingportion 42 to each other, and the linking portion 44 is raised upwardfrom the motorcycle 1 upon deployment inflation of the airbag 40 tosupport the head facing portion 42 from below. In the linking portion44, a plurality (two in the embodiment) of middle-stitched portions(also called throttle portion) 51 is provided. In the middle-stitchedportion 51, the frontal side and the backside of the airbag 40 arepartially coupled to each other to narrow the interior space. Morespecifically, along the outer edge of each of the middle-stitchedportions 51, the frontal side and the backside of the airbag 40 are madeabut on each other while reinforcing fabrics (a first reinforcing fabric63 and a second reinforcing fabric 64 will be described later) are beingplaced between the frontal side and the backside, and then thereinforcing fabrics and the frontal side and backside of the airbag 40are sewn together to form each middle-stitched portion 51.

A seam (also called stitching or stitches) 51S of the middle-stitchedportion 51 functions as a partition portion for partitioning theinternal space. As a result, gaseous matter such as gas does not enter aregion that is surrounded with the seam 51S, and therefore the regionresults in a throttle region that narrows the internal space. In thismanner, while a large head facing portion 42 is provided, the linkingportion 44 continuous with the head facing portion 42 is narrowed to asmaller space in order to facilitate quick delivery of gas into the headfacing portion 42.

In this connection, in each of FIG. 3, FIG. 4 and later-describeddrawings, seamed spots such as the seam 51S and/or the like are shown bythe dot-dot-dash lines for the purpose of clarification.

In the configuration, a plurality (two in the embodiment) of themiddle-stitched portions 51 are formed to be spaced from each other in alateral direction, so that a plurality (three in the embodiment) ofpillar-shaped gas chambers 53, 54, 55 is formed in the vehicle widthdirection, and each of the gas chambers 53, 54, 55 extends in thevertical direction. And, each of the middle-stitched portions 51 isformed in a shape in which the width is increased gradually with anextension from the neck portion 41 toward the head facing portion 42.This makes it possible to adjust dimensions of widths W1, W2, W3 of therespective gas chambers 53, 54, 55. The gas chamber 53 is formed betweenthe leftmost middle-stitched portion 51 and a left-side edge portion 40Lof the airbag 40. The gas chamber 54 is formed between the left andright middle-stitched portions 51. The gas chamber 55 is formed betweenthe right middle-stitched portion 51 and a right-side edge portion 40Rof the airbag 40. In the embodiment, the widths W1, W2, W3 are assumedas approximately constant width.

More specifically, the left and right middle-stitched portions 51 arelocated outermost in the width direction. Left and right outer seams 51Aform part of contours of the left and right middle-stitched portions 51.The left and right outer seams 51A are formed respectively parallel tothe side edge portions 40L, 40R of the airbag 40. The side edge portions40L, 40R are located outside the seams 51A in the width direction.Likewise, a pair of seams 51B forms the contours opposed to themiddle-stitched portions 51 positioned adjacent to each other. The seams51B are formed approximately parallel to each other along the verticaldirection.

As a result, the three gas chambers 53, 54, 55 are defined, and thethree gas chambers 53, 54, 55 extend linearly in constant width from theneck portion 41 toward the head facing portion 42. Accordingly, ascompared with the case where the middle-stitched portions 51 are notformed, the volume of the airbag 40 can be reduced and upsizing of theinflator 32 can be prevented.

Further, each of the gas chambers 53, 54, 55 is formed to have the samewidth W1, W2, W3 throughout from top to bottom. This makes it possibleto equalize the cross-sectional areas of the respective gas chambers 53,54, 55, and gas can be easily flown equally into the respective gaschambers 53, 54, 55. Further, the linking portion 44 is reinforcedduring deployment inflation by each gas chamber 53, 54, 55, andtherefore the advantageous effect of preventing the swaying of the headfacing portion 42 can be expected.

The widths W1, W2, W3 of the respective gas chambers 53, 54, 55 are notlimited to being exactly equal to each other, and the gas chambers 53,54, 55 may have approximately the same width. Approximately the samewidth means a width within a range in which the equivalent effects areproduced.

The left middle-stitched portion 51 includes the pair of left and rightseams 51A, 51B, a lower seam 51C and an upper seam 51D. The left andright seams 51A, 51B extend linearly. The lower seam 51C joins the lowerends of the left and right seams 51A, 51B to each other along a downwardconvex arc. The upper seam 51D joins the upper ends of the left andright seams 51A, 51B to each other along an upward convex arc. The rightmiddle-stitched portion 51 includes the pair of left and right seams51A, 51B, a lower seam 51C and an upper seam 51D. The left and rightseams 51A, 51B extend linearly. The lower seam 51C joins the lower endsof the left and right seams 51A, 51B to each other along a downwardconvex arc. The upper seam 51D joins the upper ends of the left andright seams 51A, 51B to each other along an upward convex arc.

In this manner, each of the left and right middle-stitched portions 51has the seam 51S. The seam 51S extends continuously in an endless formalong the outer edge of an oval shape (or along the outer edge of adownward protruding triangular shape). The oval shape is increased inwidth gradually toward the apex.

In the seam 51S, the lower seam 51C is formed in a downward convex form,so that the lower seam 51C has not only the function as a partition thatpartitions the inside of the airbag 40, but also the function as a lowerguide that smoothly guides the flow of gas from the bottom into each ofthe gas chambers 53, 54, 55. In turn, the upper seam 51D is formed in anupward convex form, so that the upper seam 51D has not only the functionas a partition, but also the function as an upper guide that smoothlyguides the flow of gas from each of the gas chambers 53, 54, 55 into thehead facing portion 42. Note that, although, in the embodiment, theairbag 40 is formed in bilaterally symmetric structure with respect tothe widthwise center of the airbag 40, the airbag 40 may not be limitedto being formed in the bilaterally symmetric structure.

As illustrated in FIG. 3, in base fabric 61 on the frontal side of theairbag 40 (hereinafter referred to as “frontal-side base fabric” 61), aplurality (three) of seams 56S is formed in positions corresponding tothe neck portion 41. The seams 56S extend linearly in the verticaldirection. The seams 56S are spaced in the width direction. The seams56S function as a neck-side guide that guides the gas in the upwarddirection on the frontal-side base fabric 61 side of the neck portion41. In order to form the seams 56S, the frontal-side base fabric 61 andan inside located reinforcing fabric (a later-described first layeredfabric 65 on the inflator side) are placed to abut on each other, andthen the frontal-side base fabric 61 and the inside located reinforcingfabric are sewn together.

Reference sign 57S in FIG. 3 and FIG. 4 indicates a seam at which thefrontal-side base fabric 61 of the airbag 40 and a backside base fabric62 of the airbag 40 (hereinafter referred to as “backside base fabric”)62 are sewn together. Likewise, reference sign 58S in FIG. 3 indicates aseam at which the frontal-side base fabric 61 and reinforcing fabric (alater-described first reinforcing fabric 63) are sewn together, and alsoreference sign 59S indicates a seam at which the frontal-side basefabric 61 and reinforcing fabric (the later-described first reinforcingfabric 63 and the inflator-side first layered fabric 65) are sewntogether.

Further, reference sign 71S in FIG. 4 indicates a seam at which thebackside base fabric 62 and reinforcing fabric (a later-described secondreinforcing fabric 64) are sewn together, and reference sign 72Sindicates a seam at which the backside base fabric 62 and a reinforcingfabric (the later-described second reinforcing fabric 64 and a secondlayered fabric 66 on the inflator side) are sewn together. Referencesign 73 shown in FIG. 3 and FIG. 4 indicates holes that are bored in thefrontal-side base fabric 61 and the backside base fabric 62 to effectpositioning of the frontal-side base fabric 61, the first reinforcingfabric 63, the second reinforcing fabric 64, the backside base fabric 62and the like.

The airbag 40 includes vent holes 81 (FIG. 3) in the frontal-side basefabric 61 and vent holes 82 (FIG. 4) in the backside base fabric 62. Thevent holes 81, 82 are gas outlets for the discharge of the gas from theairbag 40 in order to control the internal pressure upon the inflationdeployment.

As illustrated in FIG. 3, in the frontal-side base fabric 61, a pair ofleft and right vent holes (hereinafter referred to as “upper ventholes”) 81 is formed in the abut portion 43, and the abut portion 43 islocated upward of the head facing portion 42. The left and right ventholes 81 are open to the occupant side. The pair of left and right uppervent holes 81 is placed widthwise outward of an extended line from thelaterally centrally located gas chamber 54, and also the left and rightupper vent holes 81 are placed widthwise inward of extended lines fromthe left and right gas chambers 53, 55. With this configuration, duringdeployment inflation of the airbag 40, the upper vent holes 81 arelocated upward of the head of the occupant, so that the upper vent holes81 are not easily blocked. In addition, the upper vent holes 81 are notlocated directly above any specific gas chamber, so that, after gas hasbeen fed from each of the gas chambers 53, 54, 55 into the head facingportion 42, the gas can be readily discharged in an appropriate manner.

As illustrated in FIG. 4, in the backside base fabric 62, a pair of leftand right vent holes (hereinafter referred to as “lower vent holes) 82is formed in a position downward of the head facing portion 42. The pairof left and right lower vent holes 82 is located downward of themiddle-stitched portions 51, and also, as illustrated in FIG. 1, theleft and right lower vent holes 82 are located downward of the handlebar10 during inflation deployment of the airbag 40. With thisconfiguration, during inflation deployment of the airbag 40, the lowervent holes 82 are not blocked with the occupant, and also it is possibleto prevent the event that the lower vent holes 82 are blocked with thehandlebar 10 and other components (the visor, meters and the like)around the handlebar 10.

Also, as illustrated in FIG. 4, the pair of left and right lower ventholes 82 is placed widthwise outward of the extended line from thelaterally central gas chamber 54, and also the left and right lower ventholes 82 are placed widthwise inward of the extended lines from the leftand right gas chambers 53, 55. In short, the lower vent holes 82 areplaced at entrances of the left and right gas chambers 53, 55, exceptfor the central gas chamber 54. With this configuration, gas flowingtoward the central gas chamber 54 is not discharged from the lower ventholes 82 and then the gas can be fed into the head facing portion 42.This makes it easy to feed gas preferentially toward the widthwisecenter of the head facing portion 42.

In this manner, in the embodiment, because the vent holes 81, 82 arespaced from each other in the upper, lower, forward, backward, left andright directions, the vent holes 81, 82 are not easily blocked to enableinternal-pressure regulation on a continual basis. Note that the numberof vent holes 81 and the number of vent holes 82 may be set inconformance with requirements specification of the airbag 40, and eachof the numbers of vent holes 81, 82 may be one or may be three or more.Further, the position of each vent hole 81, 82 may be changed inconformance with requirements specification of the airbag 40.

FIG. 5 is a diagram illustrating deployment status of the airbag 40 on atime-series basis. In FIG. 5, the horizontal axis represents elapsedtime T, time T1 is a time at which the inflator 32 ignites, and time T2is a time at which deployment has been completed.

As illustrated in FIG. 5, by stretching of the airbag 40 in such amanner as to extend upward with the passage of time, the airbag 40deploys in the order of the neck portion 41, the linking portion 44 andthen the head facing portion 42 (including the abut portion 43). Asshown in the same FIG. 5, because the lower vent holes 82 are exposedfrom initial phase of deployment, the control of internal pressure inthe airbag 40 can be started at an early stage. By virtue of the lowervent holes 82, the internal pressure during the process of stretching ofthe airbag 40 is properly controlled.

Further, the upper vent holes 81 are exposed at which the deployment ofthe airbag 40 has been completed or immediately before the deployment iscompleted. Thus, after the completion of deployment, the internalpressure is regulated by the upper and lower vent holes 81, 82, so thatthe internal-pressure control at the time of contact of the occupant isproperly performed. Note that fine adjustments of size, shape andposition and the like to each vent hole 81, 82 enables fine adjustmentin the internal-pressure control.

FIG. 6 is an exploded diagram of the airbag 40.

The airbag 40 includes independently the frontal-side base fabric 61 andthe backside base fabric 62. Further, the airbag 40 includes, asreinforcing fabric, the first reinforcing fabric 63; the secondreinforcing fabric 64 that is formed in the same shape as that of thefirst reinforcing fabric 63; the inflator-side first layered fabric 65;and the inflator-side second layered fabric 66. Still further, theairbag 40 includes layered fabrics 67, 68. The layered fabrics 67, 68are laid on lower portions of the inflator-side first layered fabric 65and the inflator-side second layered fabric 66, and the layered fabrics67, 68 are provided for improvements in heat resistance and strength ina spot to which the high temperature and high pressure gas from theinflator 32 is delivered first.

As illustrated in FIG. 3, the first reinforcing fabric 63 is laid on theinner side of the frontal-side base fabric 61 and also on the region ofthe middle-stitched portion 51, and the first reinforcing fabric 63 issewn to the frontal-side base fabric 61 by the seam 58S along the outerperiphery of the first reinforcing fabric 63. The heat resistance andstrength in the region of the middle-stitched portion 51 on thefrontal-side base fabric 61 side are improved by the first reinforcingfabric 63.

As illustrated in FIG. 4, the second reinforcing fabric 64 is laid onthe inner side of the backside base fabric 62 and also on the region ofthe middle-stitched portion 51, and the second reinforcing fabric 64 issewn to the backside base fabric 62 by the seam 71S along the outerperiphery of the second reinforcing fabric 64. The heat resistance andstrength in the region of the middle-stitched portion 51 on the backsidebase fabric 62 side are improved by the second reinforcing fabric 64.

FIG. 6 shows the inflator-side first layered fabric 65 and the layeredfabric 67, and the inflator-side first layered fabric 65 and the layeredfabric 67 are laid one on top of another on the inner side of thefrontal-side base fabric 61 and also on a region where the neck portion41 is covered, and then the inflator-side first layered fabric 65 andthe layered fabric 67 are sewn to the frontal-side base fabric 61 by theseam 56S and the like as shown in FIG. 3. Thus, the strength and heatresistance in the neck portion 41 on the frontal-side base fabric 61 areimproved. In this connection, the inflator-side first layered fabric 65is laid on the region from the neck portion 41 to the first reinforcingfabric 63 to improve the strength and heat resistance in the area fromthe neck portion 41 to the middle-stitched portion 51.

The inflator-side second layered fabric 66 and the layered fabric 68 arelaid one on top of another on the inner side of the backside base fabric62 and also on a region where the neck portion 41 is covered, and thenthe inflator-side second layered fabric 66 and the layered fabric 68 arejoined to the backside base fabric 62 by sewing and/or the like. Thus,the strength and heat resistance in the neck portion 41 on the backsidebase fabric 62 are improved. In this connection, the inflator-sidesecond layered fabric 66 is laid on the region from the neck portion 41to the second reinforcing fabric 64 to improve the strength and heatresistance in the area from the neck portion 41 to the middle-stitchedportion 51.

FIG. 7 is a top view of the first reinforcing fabric 63. Incidentally,FIG. 7 shows the seams 51S, 58S for convenience in description. Notethat the second reinforcing fabric 64 is similar to the firstreinforcing fabric 63, except that the second reinforcing fabric 64 isattached to the backside base fabric 62, and therefore a repetitivedescription is omitted.

The first reinforcing fabric 63 has a shape with a width fanned outtoward the top, and the first reinforcing fabric 63 is formed into anapproximately trapezoidal sheet to cover the pair of left and rightmiddle-stitched portions 51. Between the outer edge of the firstreinforcing fabric 63 and the seams 51S of the middle-stitched portions51, space is created for the seam 58S along which at least the firstreinforcing fabric 63 is sewn. Further, the first reinforcing fabric 63has a side edge 63X on the outer side in the vehicle width direction,and assuming that value X is a separation distance between the side edge63X of the first reinforcing fabric 63 and the seam 58S, the distancebetween the lower edge of the first reinforcing fabric 63 and the seam58S is set to be greater value Y than value X (value Y>value X). Thevalue Y is set to be greater than distance Z between the seam 58S andthe seam 51S (value Y>value Z), and the seam 51S forms part of themiddle-stitched portion 51.

In other words, as compared with each of the left and right remainingmargins (corresponding to the spots of value X) of the first reinforcingfabric 63 and with the distance (corresponding to value Z) between theseams 58S, 51S, a remaining margin 91 (corresponding to the spot ofvalue Y) in a lower portion of the first reinforcing fabric 63 is set tobe longer.

Because the lower end of the remaining margin 91 is a free end, theremaining margin 91 may bend at the seam 58S as a proximal end. In thiscase, because the length Y of the remaining margin 91 is greater thanthe distance Z between the seams 58S, 51S, if the remaining margin 91bends, the remaining margin 91 can cover both the seams 58S, 51S forprotection. Note that each of the left and right remaining margins(corresponding to the spots of value X) of the first reinforcing fabric63 may not be limited to a length shorter than the remaining margin 91.

Further, in the embodiment, an upward protruding notch section 92 isformed at the widthwise center in a lower portion of the firstreinforcing fabric 63. By the notch section 92, the remaining margin 91is divided into left and right sides. Accordingly, the left and rightremaining margins 91 can bend independently, and thus the left and rightremaining margins 91 can independently protect the left and right seams51S. The left and right seams 51S are located downward of the left andright middle-stitched portions 51.

FIG. 8 is a schematic side view illustrating the frontal-side basefabric 61, the first and second reinforcing fabrics 63, 64 and thebackside base fabric 62 during airbag non-deployment. FIG. 9 is aschematic side view illustrating the frontal-side base fabric 61, thefirst and second reinforcing fabrics 63, 64 and the backside base fabric62 during airbag deployment.

Incidentally, for the purpose of clarification, a remaining margin of alower portion of the second reinforcing fabric 64 is indicated by thesame reference sign as the remaining margin 91 of the lower portion ofthe first reinforcing fabric 63. Further, in FIG. 9, the flow of gas isindicated by the arrows and the holes 73 are omitted.

As shown in FIG. 8, the length Y of each of the remaining margins 91 ofthe lower portions of the first and second reinforcing fabrics 63, 64 islonger than the separation distance Z between the seams 51S, 58S. Asshown in FIG. 9, when the airbag 40 inflates and deploys, by dilationbetween the frontal-side base fabric 61 and the backside base fabric 62,the pair of seams 58S are stretched to expose the seam 51S and the like,and therefore the seams 51S and the like are easily exposed to the gas.Incidentally, FIG. 9 shows the pair of seams 58S in a state in which theseams 58S are separated extremely from each other for the purpose ofclarification of the state.

In the configuration, as shown in the same FIG. 9, when the pair ofseams 58S is stretched, the remaining margins 91 in the lower portionsof the first and second reinforcing fabrics 63, 64 fall inward byreceiving the gas pressure. Thus, the remaining margin 91 of the firstreinforcing fabric 63 functions as a shield wall for blocking a flow ofgas toward the seam 51S on the frontal-side base fabric 61 side.Likewise, the remaining margin 91 of the second reinforcing fabric 64functions as a shield wall for blocking a flow of gas toward the seam51S on the backside base fabric 62 side. As a result, the seams 51S canbe protected from the heat of gas throughout the area between thefrontal-side base fabric 61 and the backside base fabric 62.

In addition, as illustrated in the same FIG. 9, because the remainingmargins 91 of the first and second reinforcing fabrics 63, 64 canoverlap each other, the seams 51S can be more effectively protected.Further, the seams 58S at which the first and second reinforcing fabrics63, 64 are sewn can be protected by the respective remaining margins 91.

Note that a shorter length (value Y) of the remaining margin 91 makes itdifficult for the remaining margin 91 to bend even if the remainingmargin 91 receives the gas pressure, and even if the remaining margin 91may bend, the remaining margin 91 may not sufficiently cover the seamMS. In this case, each of the remaining margins 91 does not adequatelyfunction as a gas shield wall, and therefore the remaining margin 91 isdesirably formed in a length that allows the remaining margin 91 to beable to bend by the gas pressure to cover the seams MS and the like to asufficient degree.

As described above, in the embodiment, the airbag 40 has the seams 51Sas a partition portion that partitions the interior of the airbag 40,and the seams MS are coupling spots along which the frontal-side basefabric 61 and the backside base fabric 62 are coupled with each other.The first and second reinforcing fabrics 63, 64 are provided on theinner sides of frontal-side base fabric 61 and the backside base fabric62, and the first and second reinforcing fabrics 63, 64 have theremaining margins 91, and the remaining margins 91 are oriented towardthe gas supply side in the downward direction rather than being orientedtoward the seams 51S. And, each of the remaining margins 91 functions asthe shield wall against a flow of gas toward the seam 51S.

With this configuration, the seam 51S on the frontal-side base fabric 61side can be protected by the remaining margin 91 of the firstreinforcing fabric 63, and the seam 51S on the backside base fabric 62side can be protected by the remaining margin 91 of the secondreinforcing fabric 64. Accordingly, the seams 51S can be protectedthroughout a wide region, and the proper protection of the seams 51S forpartition of the interior of the airbag 40 is enabled in a simpleconfiguration.

Further, because the remaining margin 91 of each of the first and secondreinforcing fabrics 63, 64 has a length longer than the separationdistance (value Z) between the seam 51S and the proximal end of theremaining margin 91 (corresponding to the position of the seam 58S,71S), the remaining margin 91 is able to cover the seam 51S forprotection. This enhances the function of the remaining margin 91 as ashield wall.

Here, on the gas supply side rather than on the seams 51S side, as othercoupling spots, the seam 58S and the seam 71S are possessed, the seam58S provides coupling between the first reinforcing fabric 63 (one ofreinforcing fabrics) and the frontal-side base fabric 61, and the seam71S provides coupling between the second reinforcing fabric 64 (theother reinforcing fabric) and the backside base fabric 62. The remainingmargin 91 of each of the reinforcing fabrics 63, 64 extends longer thanthe separation distance (value Z) between the seam 51S and each of theseams 58S, 71S of the reinforcing fabrics 63, 64. With thisconfiguration, each of the seams 58S, 71S, 51S is able to be protected.

Further, the seam 51S is a coupling spot along which the frontal-sidebase fabric 61 and the backside base fabric 62 are coupled to eachother, and the seam 51S is defined as a seam that provides couplingbetween a pair of base fabrics 61, 62 with the inclusion of the firstand second reinforcing fabrics 63, 64 between the base fabrics 61, 62,the pair of base fabrics 61, 62 constituting the frontal side andbackside of the airbag 40. This enables the protection of the seams 51Swhere the frontal side and backside of the airbag 40 and the reinforcingfabrics 63, 64 are coupled together.

Further, because the first and second reinforcing fabrics 63, 64 arelaid respectively on the inner sides of the frontal-side base fabric 61and the backside base fabric 62, the function of the remaining margin 91as a shield wall is enhanced.

Further, the remaining margin 91 of the first reinforcing fabric 63 andthe remaining margin 91 of the second reinforcing fabric 64 overlap eachother when both the remaining margins 91 are bent by the gas pressure,the function of the remaining margin 91 as a shield wall is furtherenhanced.

Moreover, the configuration includes the middle-stitched portions 51that provide partial coupling of the frontal side and backside of theairbag 40 to each other to narrow the internal space between the neckportion 41 and the head facing portion 42. The middle-stitched portions51 are spaced from each other in the width direction of the airbag 40.The seams 51A forming contours of the middle-stitched portions 51positioned outermost in the width direction are parallel to the sideedge portions 40L, 40R of the airbag 40 positioned outside the seams 51Ain the width direction, and the seams 51B forming contours opposed tothe middle-stitched portions 51 arranged adjacent to each other areapproximately parallel to each other.

With this configuration, while the volume of the region from the neckportion 41 to the head facing portion 42 is reduced, a plurality ofpillar-shaped gas chambers 53, 54, 55 can be formed to extend from theneck portion 41 toward the head facing portion 42. Accordingly, whileupsizing of the inflator 32 is prevented, the proper feeding of gas intothe head facing portion 42 is enabled. Note that, the phrase“approximately parallel to” means to include a range having a similarfunction without being limited to an exactly parallel state.

The separation distances (width W1, W3) between the middle-stitchedportions 51 positioned outermost in the width direction and the sideedge portions 40L, 40R of the airbag 40 positioned outside themiddle-stitched portions 51 in the width direction are equal to theseparation distance (width W2) between the middle-stitched portions 51arranged adjacent to each other. Thus, a plurality of gas chambers hasthe same width, so that the flow of gas can be easily distributed evenlyamong the individual gas chambers 53, 54, 55.

Further, because the middle-stitched portion 51 has a shape in which thewidth is increased gradually with an extension from the neck portion 41toward the head facing portion 42, the linear-shaped gas chambers 53,54, 55 are able to be formed effortlessly between the side edge portions40L, 40R of the fan-shaped airbag 40. Accordingly, the smooth feeding ofgas into the head facing portion 42 is facilitated.

Further, because the middle-stitched portion 51 is formed by sewing thefrontal side and backside of the airbag 40 together along the contoursof this middle-stitched portion 51, the middle-stitched portion 51 isable to be formed through sewing. Accordingly, any dedicated componentto form the middle-stitched portion 51 is unnecessary.

Further, because the airbag 40 is equipped with the first and secondreinforcing fabrics 63, 64 in the regions of the middle-stitchedportions 51, the regions of the middle-stitched portions 51 arereinforced, and therefore the influence of gas can be curbed.

Moreover, the airbag 40 of the configuration includes the upper ventholes 81 and the lower vent holes 82. The upper vent holes 81 are placedupward of the head facing portion 42 and also the upper vent holes 81are open to the occupant side. The lower vent holes 82 are placeddownward of the upper vent holes 81, and also the lower vent holes 82are open to the opposite side from the occupant.

With this configuration, by virtue of the lower vent holes 82, thecontrol of internal pressure in the airbag 40 is able to be performedfrom the early stage of deployment of the airbag 40, and after thedeployment completion, the internal pressure control is able to beperformed through the upper and lower vent holes 81, 82. Further,because the lower vent holes 82 are located on the opposite side fromthe occupant as well as downward of the occupant, the lower vent holes82 are hardly blocked by the occupant and/or the like, and also becausethe upper vent holes 81 are located upward of the head of the occupant,the upper vent holes 81 are not blocked by the occupant. Accordingly,the continuous control on the deployment and inflation of the airbag 40is facilitated.

Further, the upper vent holes 81 and the lower vent holes 82 areprovided in sets of two, and the two upper/lower vent holes 81, 82 arespaced from each other in the lateral direction. Because of this, theinternal pressure can be controlled properly.

Further, as illustrated in FIG. 1, the airbag 40 is located at the rearof the handlebar post 9A of the motorcycle 1, and the lower vent holes82 are placed downward of the handlebar 10 that is supported by thehandlebar post 9A. Accordingly, during inflation deployment of theairbag 40, it is possible to prevent the event that the lower vent holes82 are blocked with the handlebar 10 and other components around thehandlebar 10.

Further, in the airbag 40, an area downward of the head facing portion42 is partitioned into a plurality of gas chambers 53, 54, 55 atintervals in the width direction, and the lower vent holes 82 are placedat entrances of the gas chambers 53, 55, except for the gas chamber 54arranged in the center in the width direction. With this configuration,gas flowing toward the central gas chamber 54 is not discharged from thelower vent holes 82 and the gas can be fed into the head facing portion42. Accordingly, the effective feeding of gas toward the widthwisecenter of the head facing portion 42 is enabled.

Further, the upper vent holes 81 are placed widthwise outward of anextended line from the gas chamber 54 arranged in the center in thewidth direction, and also the upper vent holes 81 are placed widthwiseinward of extended lines from the gas chambers 53, 55 arranged outsidein the width direction. Because of this, the upper vent holes 81 are notlocated immediately above all the gas chambers 53, 54, 55. As a result,after gas has been fed from each of the gas chambers 53, 54, 55 into thehead facing portion 42, the gas is able to be discharged in a balancedmanner to facilitate controlling the internal pressure.

The above-described embodiment is provided by way of example only in oneimplementation of the present invention, and any modification and anyalternative application are possible without departing from the spiritand scope of the present invention.

For example, in the above embodiment, the case where the firstreinforcing fabric 63 is provided on the inner side of the frontal-sidebase fabric 61 and the second reinforcing fabric 64 is provided on theinner side of the backside base fabric 62 has been described. However,each of the numbers of reinforcing fabrics 63, 64 may be changed. Ifeach of the numbers of reinforcing fabrics 63, 64 to be provided is morethan one, a plurality of remaining margins 91 results, and this cancause a further enhancement in the effectiveness as gas shield walls. Ifeach of the numbers of reinforcing fabrics 63, 64 to be provided is morethan one, a remaining margin 91 of each reinforcing fabric 63, 64 on onebase fabric 61, 62 may have a different length from that of a remainingmargin 91 of each reinforcing fabric 63, 64 on the other base fabric 61,62. An example embodiment of the above case is shown in FIG. 10.

FIG. 10 illustrates an example embodiment when the remaining margins 91are different in length. FIG. 10 illustrates a schematically side viewof the frontal-side base fabric 61, the first and second reinforcingfabrics 63, 64 and the backside base fabric 62 when the airbag 40 doesnot deploy.

As shown in FIG. 10, the first reinforcing fabric 63 is situated on thefrontal-side base fabric 61, and this first reinforcing fabric 63 hasthe remaining margin 91 that is formed to have a length longer thananother remaining margin 91 of another first reinforcing fabric 63, theanother reinforcing fabric 63 being not situated on the frontal-sidebase fabric 61. The second reinforcing fabric 64 is situated on thebackside base fabric 62 and this second reinforcing fabric 64 has alsothe remaining margin 91 that is formed to have a length longer thananother remaining margin 91 (hereinafter indicated with reference sign91A) of another second reinforcing fabric 64, the another secondreinforcing fabric 64 being not situated on the backside base fabric 62(valueYl>Y>Z in FIG. 10).

As a result, the remaining margin 91A on the base fabric 61, 62 side ismore easily bent than the remaining margin 91 on the opposite side fromthe base fabric, and even when the gas pressure is relatively low, theseam 51S and the like is easily protected by the remaining margin 91A.Further, because the remaining margin 91A overlaps the remaining margin91 on the inner side of the remaining margin 91A, the effective shieldagainst gas is enabled.

In this case, the example embodiment is not limited to the method offorming both the remaining margins 91A, 91 to have a length exceedingthe above value Z, and the length may be changed as appropriate within arange that proper protection can be provided, such that the remainingmargin 91 is formed to have a length below the value Z, and the like.

Further, even when a relatively longer remaining margin 91A is notprovided, the length of the remaining margin 91 may be less than thevalue Z as long as the length is within a range that the remainingmargin 91 can provide proper protection.

Further, in the above-described embodiment, the positions, shapes and/orthe like of the first and second reinforcing fabrics 63, 64 may bechanged as appropriate in conformance with the shape or requirementsspecification of the airbag 40. Further, as to other fabrics 65, 66, 67,68 (FIG. 6) laid on the frontal-side base fabric 61 or the backside basefabric 62, the numbers of fabrics, the positions and the shapes may bechanged as appropriate.

Further, although the frontal-side base fabric 61 and the backside basefabric 62 have been described as independent components in theabove-described embodiment, the embodiment is not so limited, and thefrontal-side base fabric 61 and the backside base fabric 62 may be aone-piece sheet.

Further, the case where a plurality of gas chambers 53, 54, 55 isdefined by the middle-stitched portions 51 and the gas chambers 53, 54,55 are formed to be identical in width has been described in theabove-described embodiment, but the embodiment is not so limited.

FIG. 11 is a diagram showing an example embodiment in which a pluralityof gas chambers 53, 54, 55 is formed to have different widths.

In FIG. 11, the left and right middle-stitched portions 51 are placedcloser to the widthwise center of the airbag 40. As a result, the widthW2 of the widthwise central gas chamber 54 is shorter than the widthsW1, W3 of the gas chambers 53, 55 that are located outward in the widthdirection.

With this configuration, it is possible to expect the advantageouseffects of facilitating causing the gas to flow into the widthwiseoutward located gas chambers 53, 55, and therefore, of facilitating theretention of the outer shape of the airbag 40 during airbag deployment.Note that the width W1, W2, W3 of each gas chamber 53, 54, 55, thecross-sectional shape of each gas chamber 53, 54, 55, and/or the likemay be changed as appropriate in conformance with requirementsspecification of the airbag 40.

Further, although the case of providing a pair of left and rightmiddle-stitched portions 51 has been described in the above-describedembodiment, the embodiment is not so limited, and three middle-stitchedportions 51 or more may be provided at intervals in the width direction.

Further, although the case of coupling individual portions of the airbag40 to each other by means of sewing has been described in theabove-described embodiment, the embodiment is not so limited, and acoupling method other than sewing may be applied. For example, awell-known coupling method, such as a joining method including weldingand the like can be widely applied.

Further, although the application of the present invention to the airbagdevice 30 of the motorcycle 1 has been described, the present inventionis not so limited, and the present invention may be applied to airbagdevices used in vehicles other than motorcycles. For example, thepresent invention may be applicable to airbag devices used in saddleriding vehicles and the like. The saddle riding vehicles include thevehicles in general, of which a rider/driver rides astride the vehiclebody, and the vehicles are not limited to motorcycles (includingmotorized bicycles), and the vehicles include other two-wheeled vehiclessuch as bicycles and the like, three-wheeled vehicles such as ATV (AllTerrain Vehicles) and the like, and four-wheeled vehicles.

REFERENCE SIGNS LIST

1 Motorcycle (saddle riding vehicle)

30 Airbag device

40 Airbag

40L, 40R Side edge portion

41 Neck portion

42 Head facing portion

51 Middle-stitched portion (throttle portion)

51S, 57S, 58S, 71S, 72S Seam (partition)

53-55 Gas chamber

61 Frontal-side base fabric

62 Backside base fabric

63 First reinforcing fabric

64 Second reinforcing fabric

81 Upper vent hole

82 Lower vent hole

91, 91A Remaining margin

92 Notch section

W1-W3 Width

The invention claimed is:
 1. An airbag device, comprising an airbag anda partition element, the airbag being made of frontal and backside basefabrics and formed in a bag shape to deploy by being supplied with gas,the partition element partitioning the interior of the airbag, whereinthe frontal base fabric and the backside base fabric compose an outerside of the airbag, the airbag device includes a frontal reinforcingfabric that is coupled to an inner side face of the frontal base fabricof the airbag at a first coupling spot, and a backside reinforcingfabric that is coupled to an inner side face of the backside base fabricof the airbag at a second coupling spot, the airbag device has, as thepartition element, a frontal-backside coupling spot along which thefrontal base fabric, the frontal reinforcing fabric, the backsidereinforcing fabric, and the backside base fabric are coupled directly toeach other in a layered arrangement with the frontal reinforcing fabricin surface abutment with the frontal base fabric and the backsidereinforcing fabric, and the backside reinforcing fabric in surfaceabutment with the backside base fabric and the frontal reinforcingfabric such that gas to deploy the airbag is prevented from separatingany of the frontal base fabric, the frontal reinforcing fabric, thebackside reinforcing fabric, and the backside base fabric from eachother in the frontal-backside coupling spot, the first coupling spot andthe second coupling spot are provided respectively closer to a gassupply side than the frontal-backside coupling spot, each of thereinforcing fabrics has a remaining margin that protrudes from the firstcoupling spot and the second coupling spot toward the gas supply side,the remaining margin is a free end of fabric that is bent to an inwarddirection of the airbag at the first coupling spot and the secondcoupling spot along proximal seam ends thereof by gas pressure in orderto function as a shield wall against a flow of gas toward thefrontal-backside coupling spot.
 2. The airbag device according to claim1, wherein the remaining margin of each of the reinforcing fabrics islonger than a separation distance between a proximal end of theremaining margin and the frontal-backside coupling spot.
 3. The airbagdevice according to claim 1, wherein a frontal-reinforcing coupling spotcouples the frontal reinforcing fabric and the frontal base fabric and abackside-reinforcing coupling spot couples the backside reinforcingfabric and the backside base fabric, wherein the frontal-reinforcingcoupling spot and the backside-reinforcing coupling spot are both in alocation closer to the gas supply side than the frontal-backsidecoupling spot, and wherein a distance from an outer peripheral edge ofthe frontal reinforcing fabric to the frontal-reinforcing coupling spotis greater than a distance between the frontal-reinforcing coupling spotand the frontal-backside coupling spot and a distance from an outerperipheral edge of the backside reinforcing fabric to thebackside-reinforcing coupling spot is greater than a distance betweenthe backside-reinforcing coupling spot and the frontal-backside couplingspot.
 4. The airbag device according to claim 1, wherein the frontal andbackside reinforcing fabrics are sandwiched between the frontal andbackside base fabrics at the frontal-backside coupling spot.
 5. Theairbag device according to claim 1, wherein frontal and backsidereinforcing fabrics each are a plurality of fabrics that are laid one ontop of another on the inner side of the frontal base fabric and theinner side of the backside base fabric respectively.
 6. The airbagdevice according to claim 5, wherein the plurality of fabrics of thefrontal reinforcing fabric have remaining margins of different lengthswith the lengths decreasing for each layer of fabric of the plurality offabrics as laid one on top another in an outside-to-inner sidedirection.
 7. The airbag device according to claim 1, wherein theremaining margins of the frontal and backside reinforcing fabricsoverlap each other when bent by pressure of the gas.